Year: 2008

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“Our results are not good news for those living in the western United States.”
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Science/www.sciencexpress.org / 31 January 2008 /

Human-Induced Changes in the Hydrology of the Western United States

Tim P. Barnett,1* David W. Pierce,1 Hugo G. Hidalgo,1 Celine
Bonfils,2 Benjamin D. Santer,2 Tapash Das,1 Govindasamy Bala,2 Andrew
W. Wood,3 Toru Nozawa,4 Arthur A. Mirin,2 Daniel R. Cayan,1 Michael
D. Dettinger1

1 -Scripps Institution of Oceanography, University of California, San
Diego, La Jolla, CA 92093, USA.
2 -Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
3 -Land Surface Hydrology Research Group, Civil and Environmental
Engineering, University of Washington, Seattle, WA 98195, USA.
4 -National Institute for Environmental Studies, 16-2, Onogawa,
Tsukuba, Ibaraki 305-8506, Japan.

*To whom correspondence should be addressed. E-mail: tbarnett-ul@ucsd.edu

ABSTRACT: Observations have shown the hydrological cycle of the
western U.S. changed significantly over the last half of the
twentieth century. Here we present a regional, multivariable
climate-change detection and attribution study, using a
high-resolution hydrologic model forced by global climate models,
focusing on the changes that have already affected this primarily
arid region with a large and growing population. The results show up
to 60% of the climate related trends of river flow, winter air
temperature and snow pack between 1950-1999 are human-induced. These
results are robust to perturbation of study variates and methods.
They portend, in conjunction with previous work, a coming crisis in
water supply for the western United States.

CONCLUSIONS:
Our results are not good news for those living in the western United
States. The scenario for how western hydrology will continue to
change has already been published using one of the models employed
here [PCM (2)] as well as in other recent studies of western US
hydrology [e.g., (15)]. It foretells of water shortages, lack of
storage capability to meet seasonally changing river flow, transfers
of water from agriculture to urban uses and other critical impacts.
Since PCM performs so well in replicating the complex signals of the
last half of the 20th century, we have every reason to believe its
projections and to act on them in the immediate future.

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Deforestation of Amazon has soared by 69% in a year
THE ASSOCIATED PRESS

RIO DE JANEIRO, Brazil — Amazon deforestation jumped 69 percent in the past 12 months — the first such increase in three years — as rising demand for soy and cattle pushes farmers and ranchers to raze trees, officials said Saturday.
Some 3,145 square miles of forest were destroyed between August 2007 and August 2008 — a 69 percent increase over the 1,861 square miles felled in the previous 12 months, according to the National Institute for Space Research, or INPE, which monitors destruction of the Amazon.
“We’re not content,” Environment Minister Carlos Minc said. “Deforestation must fall more and conditions for sustainable development must improve.”

Brazil’s government has increased cash payments to fight illegal Amazon logging this year, and it eliminated government bank loans to farmers who illegally clear forest to plant crops.
The country lost 2.7 percent of its Amazon rain forest in 2007, or 4,250 square miles. Environmental officials fear even more land will be razed this year — but they have not forecast how much.
Minc says monthly deforestation rates have slowed since May, but environmental groups say seasonal shifts in tree cutting make the annual number a more accurate gauge.

Most deforestation happens in March and April, the start of Brazil’s dry season, and routinely tapers off in May, June and July: Last month, 125 square miles of trees were felled, 61 percent less than the area razed in June.
Environmentalists also argue that INPE’s deforestation report wasn’t designed to give accurate monthly figures, but to alert and direct the government to deforestation hot spots in time to save the land.
The Amazon region covers about 1.6 million square miles of Brazil, nearly 60 percent of the country. About 20 percent of that land has already been deforested.

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